Normalize PWD environment variable before using it

In commit 5aed3ee49d (cmSystemTools: Add GetLogicalWorkingDirectory,
2024-10-28, v4.0.0-rc1~528^2~6) we incorrectly trusted `PWD` to be a
normalized path so long as its realpath matches the current working
directory.

Fixes: #26870

Source/cmSystemTools.cxx

@@ -3007,10 +3007,11 @@ std::string InitLogicalWorkingDirectory()
 {
   std::string cwd = cmsys::SystemTools::GetCurrentWorkingDirectory();
   std::string pwd;
-  if (cmSystemTools::GetEnv("PWD", pwd)) {
+  if (cmSystemTools::GetEnv("PWD", pwd) &&
+      cmSystemTools::FileIsFullPath(pwd)) {
     std::string const pwd_real = cmSystemTools::GetRealPath(pwd);
     if (pwd_real == cwd) {
-      cwd = std::move(pwd);
+      cwd = cmSystemTools::ToNormalizedPathOnDisk(std::move(pwd));
     }
   }
   return cwd;

Tests/RunCMake/CommandLine/RunCMakeTest.cmake

@@ -896,10 +896,31 @@ run_cmake_command(E_sleep-bad-arg2 ${CMAKE_COMMAND} -E sleep 1 -1)
 run_cmake_command(E_sleep-one-tenth ${CMAKE_COMMAND} -E sleep 0.1)
 
 run_cmake_command(P_directory ${CMAKE_COMMAND} -P ${RunCMake_SOURCE_DIR})
-run_cmake_command(P_working-dir ${CMAKE_COMMAND} -DEXPECTED_WORKING_DIR=${RunCMake_BINARY_DIR}/P_working-dir-build -P ${RunCMake_SOURCE_DIR}/P_working-dir.cmake)
-# Documented to return the same result as above even if -S and -B are set to something else.
-# Tests the values of CMAKE_BINARY_DIR CMAKE_CURRENT_BINARY_DIR CMAKE_SOURCE_DIR CMAKE_CURRENT_SOURCE_DIR.
-run_cmake_command(P_working-dir ${CMAKE_COMMAND} -DEXPECTED_WORKING_DIR=${RunCMake_BINARY_DIR}/P_working-dir-build -P ${RunCMake_SOURCE_DIR}/P_working-dir.cmake -S something_else -B something_else_1)
+
+block()
+  set(expect ${RunCMake_BINARY_DIR}/P_working-dir-build)
+  run_cmake_script(P_working-dir -DEXPECTED_WORKING_DIR=${expect})
+
+  # -S and -B have no effect on script mode variables.
+  set(RunCMake_TEST_VARIANT_DESCRIPTION "-S-B")
+  run_cmake_script(P_working-dir -DEXPECTED_WORKING_DIR=${expect} -S something_else -B something_else_1)
+
+  # Relative PWD is ignored.
+  set(RunCMake_TEST_VARIANT_DESCRIPTION "-PWD-.")
+  set(RunCMake_TEST_COMMAND_PWD .)
+  run_cmake_script(P_working-dir -DEXPECTED_WORKING_DIR=${expect})
+
+  # Lower-case PWD is ignored on case-sensitive filesystems
+  # and case-normalized on case-insensitive filesystems.
+  set(RunCMake_TEST_VARIANT_DESCRIPTION "-PWD-case")
+  string(TOLOWER "${expect}" RunCMake_TEST_COMMAND_PWD)
+  run_cmake_script(P_working-dir -DEXPECTED_WORKING_DIR=${expect})
+
+  # Backslashed PWD is normalized on Windows and ignored elsewhere.
+  set(RunCMake_TEST_VARIANT_DESCRIPTION "-PWD-backslash")
+  string(REPLACE "/" "\\" RunCMake_TEST_COMMAND_PWD "${expect}")
+  run_cmake_script(P_working-dir -DEXPECTED_WORKING_DIR=${expect})
+endblock()
 
 # Place an initial cache where C_basic will find it when passed the relative path "..".
 file(COPY ${RunCMake_SOURCE_DIR}/C_basic_initial-cache.txt DESTINATION ${RunCMake_BINARY_DIR})

Tests/RunCMake/RunCMake.cmake

@@ -164,8 +164,12 @@ function(run_cmake test)
   else()
     set(old_pwd)
   endif()
-  # Emulate a shell using this directory.
-  set(ENV{PWD} "${RunCMake_TEST_COMMAND_WORKING_DIRECTORY}")
+  if(RunCMake_TEST_COMMAND_PWD)
+    set(ENV{PWD} "${RunCMake_TEST_COMMAND_PWD}")
+  else()
+    # Emulate a shell using this directory.
+    set(ENV{PWD} "${RunCMake_TEST_COMMAND_WORKING_DIRECTORY}")
+  endif()
   cmake_language(EVAL CODE "${_code}")
   if(DEFINED old_pwd)
     set(ENV{PWD} "${old_pwd}")